1. Field of the Invention
The present invention relates to a silo, in particular a vertical one, designed to store products in powder form, and having a vibrating bottom, in particular one of a frustoconical shape, suitable for favoring the flow of the material.
Although more especially developed in connection with the silo storage of finely ground powder, the invention will also find an application in all sectors of industrial activity in which there is a need to have material kept from spontaneous discharge solely through the effect of gravity transported in containers, hoppers or the like.
2. Description of the Related Art
When solid products such as, in particular, flours or talc having a grain size of less than one millimeter are stored in silos, the force of gravity does not spontaneously cause the products to flow.
Such powders, which are subjected to the pressure exerted by their own weight, form, form a vault, in the lower portion of the silo, which is generally frustoconical in shape. The vault blocks the lower orifice of the silo through which the powder ought to flow.
Thus, if it is wished to extract material from the silo, the first thing to be done is to break down the vault formed by the product in powder form.
In this respect, one of the known techniques is to place, in the portion of the cone of the silo in which the vault forms, an element known as a `vibrating bottom`.
This element can further be internally equipped with a central deflector absorbing the static loads of the product stored in the silo, in particular the pressure due to its weight.
This being the case, to enable the material to flow by breaking down the vault, the entire bottom of the silo and, more precisely, its outer envelope, are caused to vibrate by means of an unbalanced motor.
This vibration, which diffuses through the stored product, enables the particles to shift in relation to one another and thus transition from the friction state to the sliding state. These changes of state facllitate flow.
With this type of equipment, it is necessary to prevent the vibrations of the frustoconical element at the bottom of the silo equipped with a vibrating bottom from being transmitted to the rest of the silo body.
Over widely diffused vibration in the bottom portion of the stored products can, in fact, lead to the settling, or agglomeration, of the solid products throughout the silo, which would be counter to the object of the exercise.
For this purpose, it is known to use a vibrating bottom comprising a plane, peripheral, upper rim, provided opposite a corresponding lower rim of the silo, with a view to their connection, this being accomplished via a relatively flexible connecting and damping element, cooperating with independent connecting means interposed between said lower and upper rims, in such a way as to ensure a tight connection between the silo and its vibrating bottom while, at the same time, preventing vibrations from being transmitted from one to the other.
In one type of known equipment, the connecting, or joining, element takes the form of a peripheral joint with a U-shaped cross-section, opening outwardly and interposed between the bottom portion of the silo and the vibrating bottom. The joining element, the bottom portion of the silo and the vibrating bottom are connected via two flat flanges, independent of one another, designed to be mounted against the upper and lower horizontal wings of the U-shaped joint to press them against the lower and upper rims.
In this device, once the joint is in position between the respective peripheral rims of the bottom portion of the silo and of the vibrating bottom, it is fixed by means of two series of bolts, placed close together and passing equidistantly through each of the peripheral rims, to cooperate by clamping with each of the flanges after passing through the horizontal wings of the U-shaped joint and thus clasp it in place.
The installation of such a known joint in fact only ensures tightness between the bottom portion of the silo and the vibrating bottom.
More specifically, the vibrating bottom is fixed in relation to the silo, and the vibrations are damped, via four silentblocs, or shock mounts, diametrically opposed two by two, cooperating with four support points provided on the lower rim of the silo, opposite four other support points provided on the upper rim of the vibrating bottom.
In this known device, the entire weight of the vibrating bottom, and of any product that may be contained therein, is thus borne by the four shock mounts.
To provide and implement this technique on the silo adds to the cost of the latter and, what is more, stresses are consequently localized at four points only, which necessitates reinforcement, in particular by means of gusset plates mounted around the lower portion of the silo, and thick metal plating.
Furthermore, with this same device, it is necessary to provide two independent flanges, which represent additional parts, necessitating special Installation, thus leading to increased labor requirements.